Rotary drill bit



Patented 8, 1925.

UNITED STATES mm o'rIs uoonn, or wnwoxn, OKLAHOMA.

ROTARY DRILL BIT.

Application filed November-.6, 1924. Serial No. 748,202.

provements in rotary rill bits of the socalled fish-tail type ofconstruction, and it consists in the combinations, constructions andarrangements herein described and claimed.

As is well known, a drill bit of the above mentioned type ofconstruction ordinarily is formed with the head thereof provided with apair of integral depending cutter extensions which soon beoome dull inuse, necessitating the removal of the entire bit for resharpening of thecutter portions thereof.

Ordinarily, it is necessary that the bit he 2 heated in a suitablefurnace, and then provided with a sharp edge and tem red after the bithas become dull. It will appreciated that a considerable delay in thedrilling operation may result froni the necessity 80 of removing theonly availableibits for resharpening and repair or else a considerablesupply of sharp bits must bekept on hand at all times, which would causeconsiderable expense.

An object of the present invention is to provide a drill bit of thecharacter described which has simple, inexpensive and readily removablecutter members supported on the head of the drill bit and adapted to bere- 40 placed quickly and without the use of any special tools whenrequired.

A further ob'ect of the invention is the provision of a rill bit of thecharacter described which has means for cutting in ad- 46 vance of thebit head at the center of the drill bore as well as at theouter edge ofthe drill bore.

A further object of the invention isthe provision of a. drill bit havinga central cut- 50 ter element mounted to rotate about an axisarticularly to im-' which extends at right angles to the longitudmalaxisg of the drill bit and being" adj ustable about its axis of rotationto vary the ortion of the cutting edge therwf that will (pbresentedtothe work. 7

her objects and advantages will be apfparentfrom the followingdescription, considered in conjunction with the accompanym drawmgs, inwhich,

igure 1 is a side elevation .of a drill bit 00 embodying the inventionapplied to thelower end of a drill stem, I

Figure 2 is an elevation of the structure shown in Figure 1, the viewbeing at right angles to Figure 1, V

Figure 3 is a bottom plan view of the im proved drill bit, and

Figure 4' is a perspective group view ShOWlIl the cutter members of thedrill bit and a s aft for supporting one of said cut- 10.

tom.

A drill bit embodying the invention has ahead 1' formed with a, reducedtapering axial attaching portion or shank 2 at the normally upper-endthereof. The attach- 7' ing ortion or shank 2 is shown as being providedwith external screw threads for engaging with an internally screwthreaded tapering axial socket 3 in the lower end of a drill stem 4, ashoulder 5 being defined so at the juncture of the shank 2 and the head1 for engagement with the lower end of the drill steml-4 when the shank2 has been screwed ti ht in the socket 3. Any thrust from the (f to thehead 1 through the shoulder '5 without any undue strain of the threadedconnection between the shank 2 and the drill stem 4,

The head 1 is provided at its lower end 00 with a 'pair of dependingintegral exten sions 6. The lower end portions of the respectiveextensions 6 are shown as extending laterally of the bit head. The innerside faces of, the respective extensions 6 are shown as lying in avertical plane which extends centrally of the bit head while the outerfaces of the extensions referably are convexly curved or rounded 0 attheir lower ends and at their outer lateral edges as rill stem 4 thuswill be imparted as 10 to conform to the inclination from the horizontalof the upper wall 8 of its seat. Each of the cutter plates 9 also hasthe lower end Wall thereof beveled as indicated at 11 and has the outerface thereof concavely curved as indicated at 12 so that the outer edgeof the lower end wall of the cutter plate is a sharp cutting edge.

Each cutter blade 9 is secured in place in its seat by means of a bolt13 and nut 14 or like fastening means so that the beveled upper end wallof the cutter plate will fit closely against the inclined upper wall ofthe seat and the lower end portion of the cutter plate will dependslightl below the level of the extension 6 on whic the cutter plate issupported. -The cutter plate thus will be held rigid with the extension6 on which it is supported but can be removed quickly and easily for thepurpose of replacement or repair. The thickness of the cutter platepreferably is such that the outer face thereof will be substantiallyflush with the inner face of the extension 6 on which it is supported.Each cutter plate also has the outer lateral wall thereof beveled asiicildicated at 15 to provide a lateral cutting e ge.

With the arrangement of depending extensions spaced apart as describedin the foregoing, a vertical space or aperture will be defined at thelower end of the bit head as indicated at 16 between the inner lateralwalls of the extensions 6. A horizontal shaft 17 extends transverselyacross the space 16 and has the end portions thereof supported inaligned seats indicated generall at 18 each of which may be formed party in an inner face of one of the extensions 6 and partly in the adjacentface of the cutter plate 9 which is secured to that particular extension6, the portion of the seat 18 that is formed in the extension 6 ofcourse bein in the vertical wall of the rabbet 7 of sai extension sothat the shaft 17 will be held against displacement from position toextend across the space 16 so long as the cutter plates 9 are heldagainst displacement from the rabbets 7. Removal of the cutter plates 9will. permit displacement of the shaft 17. A circular cutter 19 havingthe cutting edge thereof located intermediate its ends is su ported onthe shaft 17 to rotate about t e axis of the latter and is held againstaxial ment of the ends of the cutter 19 with the inner lateral wall ofthe extension 6.

From the foregoing description of the various parts of the device, theoperation thereof may be readily understood. The cutter plates 9 and thecircular cutter 19 are made of suitable material, such as a high gradetool steel. These cutters are comparatively small and therefore can bereplaced when required at slight expense. Moreover, the replacement ofthe cutters 9 and 19 or an one of these cutters can be effected quicklyand easily withoutthe use of any special tools. The cutting edge portionof the drill cutter 19 depends below the lower cutting edges of theplates 9 and thus serves to start the drilling of a bore at the centerof the latter before the lateral cutters 9 cut into the earth. Thecutter 19 can be turned from a given position to present a differentportion of the annular cutting edge thereof to the work when the portionof the cutting edge that has been in use has become dull.

Obviously, my invention is susceptible of embodiment in forms other thanthat illustrated in the accompanying drawings and I therefore consideras my own all such modifications and adaptations of the form of thedevice herein described as fairly fall within the scopeof the appendedclaims.

I claim:

1. A rotary drill bit comprising a head formed with a pair of spacedapart depending extensions at the lower end thereof, said extensionsbeing located eccentrically of the bit head and having the inner facesthereof disposed in a vertical plane which'extends centrally of the bithead, each of said extensions having a seat in its inner face at thelower end thereof for a cutter plate, means for releasably securing saidcutter plates to said extensions in engagement with their seats, and acircular cutter supported between said extensions for rotation about anaxis which extends at right angles to the longitudinal axis of the bithead.

2. A rotary drill bit comprising a head formed with a pair of spacedapart depending extensions at the lower end thereof, said extensionsbeing located eccentrically of the bit head and having the inner facesthereof disposed in a vertical plane which extends centrally of the bithead, each of said extensions having a seat in its inner face at thelower end thereof for a cutter plate, means for releasably securing saidcutter plates to said extensions in engagement with their seats, a shaftextending between said of said shaft, said circular cutter dependintensions and serving to clamp the opposite below the level of the loweredge of sai edge portions of said shaft to said extensions 10 cutterplates. i i so that the shaft extends across the space 3. A rotary drillbit comprising a head' between the extensions and a circular cutter 5formed with a pair of spaced depending exsupported on said shaft forrotation between tensions'at the lower end thereof,- a shaft of saidextensions.

greater length than the distance between said v extensions, cutterplates secured to said ex- RALPH OTIS MOORE.

